Eventually all of this will be linked from the individual calculator pages but I'm looking for errors and omissions before I do that. I'm especially lacking features found in ROMS or pacs for the desktop calculators and a few of the handhelds. Please send any information/corrections.

Well, the first thing I noticed was that a lot of the links on the features page were wrong. The HP-16C was linked to the 19C, the 19C goes to the 22, the 41C goes to the 9100B, the 91 goes to the 15C, etc. I had fun clicking on models and guessing where I'd end up. :-) I really like this idea, though, and the indicdual pages are very nice.

The comparison stuff is great. I haven't had time to go through a lot of it, but it looks very good and is attractively formatted. My only suggestion would be to add some newer models if possible. I'd love to be able to generate a chart showing how well the older models stack up against the current offerings in real-world applications.

On another subject: I've been so busy that I haven't had a chance to scan that plotter manual I promised you. However, I've taken tomorrow off from work to catch up on a few things, and getting that manual scan finished is on the top of my list.

Excellent job, your selection of categories and the overall look are very useful. Since you have the year of introduction, it would be nice to include the year of discontinuation. I would also like to see a field for self test, and if valid, the keystrokes to activate it. The end notes of the HP-81 mention it is a printing version of the HP-81 not 80. Thanks for all your work!

As long as you are cataloging each calculator's features, why not document known bugs for each model? Most of us use Craig A. Finseth's HPDATAbase to research this type of information. However, it would be nice to have it canonized in the MoHPC.

I liked the new features and comparison pages. Just some suggestions/corrections:

HP25: While it is true that is does storage arithmetic, it does not have "recall arithmetic" ie: it has STO+0, STO*5, but no RCL+1. Other models have RCL arithmetic, if memory helps, even the HP45 did. Opcode space limits may have been a cause for this, since each merged keystroke was to be coded in one single byte, so there were only 255 possible opcodes, and recall arithmetic would have consumed 32 opcodes.

HP25: The link at the bottom of the HP25 page leads to the HP21, not to the HP25C, as supposed.

HP41C: No suggestions.

HP42S: It does NOT has overlays or magcards to define softkeys, only softlabels on the display menu.

HP42S: Sum of lists IS supported. First edit a matrix, and then press the Sigma key with the matrix object in the x register.

I had just reviewed my estimation about opcodes for the HP25, and it seems there were enough free opcodes for recall arithmetic. This corrects my previous suggestion about why HP did not implemented that feature in the HP25. ROM space may be a cause, but I don't have any precision on this. The HP Journal article that introduced the -20 series suggests that, once defined the hardware (CPU, RAM and ROM capacity), then the design teams discuss what functions to implement within the available ROM. Despite programming and developing costs, it was clear that "code" does not add to the production cost of each unit, while chips do.

I don't list RCL arithmetic because it's a rather obscure (and in my opinion not overly useful) feature. The HP-45 was one the very few to support it. I suppose, that an argument for listing RCL arithmetic can be made BECAUSE of its rarity. How do other people feel about this?

I would like to see the RCL arithmetic option in the features list because it is an unusual feature found on only a handfull of HP calculators. I believe the models that had RCL arithmetic were the 45, 46, 27, 15C, 32S, 42S, and 32SII. And I would have to respectfully disagree with you regarding it's usefulness. I have found that recall arithmetic is quite useful in many programs.

Also, I believe the HP-27S was the only calculator to do exponentiation (STO ^ nn) as part of storage arithmetic (but not recall arithmetic). Perhaps a footnote on the 27S features page could point this out.

I love the comparison page! It is great to be able to compare the calculators side by side. I know you are a busy guy, but I would love to see that info on some of the newer models also such as the 38G, 48S, 48SX, 48G, 48GX and that new TI clone. That way we could compare the great oldies right along side some of the newer models. It is just a suggestion....